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Mplus Discussion > Confirmatory Factor Analysis >
 akiko tanabe posted on Tuesday, July 20, 2010 - 11:57 am
I am getting an error message when performing a CFA multiple group analysis (comparing males and females) using the following syntax:

Factor1 BY var1 var2 var3 var4;
Factor2 BY var5 var6 var7;
Factor3 BY Factor1 Factor2;

Factor3 represents a "dimensional" factor which comprises factors 1 and 2.

The first two syntax lines run fine but the "Factor3" seems to be the problem - as suggested by the Tech printout. I don't have any problems when running the 3 syntax commands on either the male or female group data individually. But when I run the syntax across both groups (using mgroup)that's when the problem occurs.

Could you advise please?
 Linda K. Muthen posted on Tuesday, July 20, 2010 - 2:22 pm
A second-order factor must have at least three first-order factors for the model to be identified. Your model is not identified.
 akiko tanabe posted on Wednesday, July 21, 2010 - 7:40 pm
Thank you for the help, Dr. Muthen. I don't understand, though, why the second-order factor worked when using data from one group (e.g., males). No error messages was generated. It seemed to have worked with two (not three) first-order factors.

But now the second-order factor with two-first-order factors does not work when using data with both groups (males and females). Could you please explain why the second-order factor having two first-order factors worked in one case but not the other?

Thank you very much.
 Linda K. Muthen posted on Wednesday, July 21, 2010 - 9:14 pm
You must have had some other restriction in the earlier model. I would have to see both outputs to see what the difference is. A second-order factor model with two first-order factor indicators is not identified.
 akiko tanabe posted on Thursday, July 22, 2010 - 9:26 am
I will send you the outputs. Thank you, Dr. Muthen!
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